Thoughts about the efficiency of vacuum desalination - seems pointless

[MasterBlaster]

I've been thinking about whether switching to vacuum desalination actually makes sense (This is after Research Lab 4 so new players might be a ways away from it). But anyway, it occurred to me that the gains you get are counteracted and so the whole thing is somewhat pointless and counter-productive.

So here's the thing. When you switch to vacuum Desal recipe, you're now using steam depleted instead of steam high. Great, less steam high means less fuel burned. Big savings. But there's a large problem - the recipe takes twice as long as the normal, steam high/low recipe.
So because it takes twice as long, that means you now need twice as many de-sal plants to make the same amount of water. And this wouldn't be a problem if it weren't for the fact that they use 400 KW each.
So say you've got 8 of these plants, using 3200KW of power. You switch them all over to vacuum, and so in order to keep up the water you build out your plants to be 16 in total. Now they're using 6400KW of power. So sure you're burning less fuel to provide the steam, but you're also burning more fuel to provide the extra electricity. They just cancel each other out, and in the end it's not any more efficient than using a big cooling tower.

Is my math wrong on something? Is it just nice because you no longer need the big cooling tower? I can't see any other benefit.

[Kaery]

I use the vacuum desalination behind my power plant. Not because I don't like the big cooling tower, I actually have enough of those on hand in case the water backfills, but because it makes my powerplant water positive, instead of negative.

Water production is not the primary point why I use it, the point is to have a water supply for my power plant that feeds itself.

[MasterBlaster]

oh I see yeah that does make sense. If you're only using the water for power and nothing else then you don't need any fuel to keep the water cycling.